Australian scientists are getting help from elephant seals to build a greater understanding of climate change. The marine mammals carry sensors that transmit data about ocean currents and sea ice. From Sydney, Phil Mercer reports.

Scientists have long thought that the vast areas of sea ice in Antarctica could help them unlock some of the secrets of climate change.

The ice reflects sunlight back into space. With global temperatures rising, there are concerns that polar ice is shrinking, and, as it does, additional energy is absorbed by the earth, causing more warming.

For the first time, researchers have been able to gather crucial information from the heart of this icy wilderness thanks to help from an unlikely source - 85 elephant seals.

The seals were fitted with special satellite sensors that sent back data from Antarctica. The devices are the size of a mobile phone and eventually fall off when the animals shed their fur in summer.

Between 2004 and 2005, the seals each swam up to 65 kilometers a day, supplying scientists with thousands of pieces of information about the sea ice that ocean buoys and ships have been unable to provide.

Steve Rintoul, from the Australian government's Commonwealth Scientific and Industrial Research Organization (CSIRO) says the seals have been invaluable.

"The polar regions are barometers of change for the climate of the earth as a whole. The 19 million square kilometers of sea ice that form each winter had been a blind spot so far and the seals help us fill in that part of the story," Rintoul said.

The elephant seals, which can dive to depths of 15-hundred meters, have provided a 30-fold increase in data from parts of the Southern Ocean. The research also involved teams from the United States, Great Britain and France.

The antennas placed on the animals' heads detail shifts in sea currents and record changes in water temperature as well as salinity. The data helps chart the effects of climate change under the Antarctic ice.

Changes in salinity are used to calculate how much sea ice is formed during the winter months.

Mark Hindell, a seal biologist at the University of Tasmania, says this unusual research method does not harm the seals.

"Animals that carry tags are just as good at foraging, just as good at catching food as animals without them," Hindell said. "Longer term, they have just the same sort of survival rates as animals that don't carry them. So, there's no effect on the seals and the few seals that are out there collecting this data are doing an enormous service, if you like, to broader science and also to their own species."

Scientists have not been able to draw firm conclusions about changes from the data the seals collected, because there is nothing to compare it with. But the information will provide a basis for future studies.

Researchers now plan to use other seal species in different parts of the Arctic and Antarctic in the quest for a greater understanding of a changing climate.

The polar regions play an important role in the Earth's climate system. Scientists have said they are changing more rapidly than any other part of the planet.